The HIV Center for Clinical and Behavioral Studies at the New York State Psychiatric Institute and Columbia University is committed to interdisciplinary research on behaviors critical to HIV infection and the consequence of HIV disease. In this resubmission, we propose to continue our research for the next five years, building on a strong record of accomplishments; of stimulating new research in HIV/AIDS through consultation and collaboration; and of providing training and exchange with local, national, and international communities. We propose four research projects: 1) Peer Activism for Female Partners of Injection Drug Users; 2) High-Risk Latino Men: An empowerment Program to Reduce Unsafe Sex; 3) Disclosure Skills for HIV+ Pregnant and Post-Partum Women; and 4) Promoting Antiviral Medication Adherence in HIV Clinics. In addition to the Administrative Core, four research cores will provide expertise to Center investigators and affiliated colleagues: the Statistics, Epidemiology and Data Management Core; the Psychosexual Core; the Psychosocial/Qualitative Assessment Core; and the Information Exchange Core, which will include an international component to develop an infrastructure for collaboration on research in South African and Brazil. The significance of the proposed HIV Center III is multifold: 1) The research will advance our understanding of the effectiveness of new intervention approaches based on innovate theories and techniques such as peer activism, empowerment, and peer counseling. 2) We will specifically further our knowledge on recruiting and retaining female sexual partners of injection drug using men for a multi-session intervention in the community. 3) We will test an innovative intervention for newly immigrated Latino men who have sex with men in partnership with a Latino community organization. 4) We will test an intervention to enhance disclosure skills among HIV+ pregnant and post-partum women who are informed of their HIV status through a new New York State mandate. 5) We will conduct a clinic- based intervention that is nurse-delivered to promote adherence of antiviral therapies in two inner-city hospitals and will document adherence based on self-report and biological indicators. 6) We will develop an international program of research collaboration with colleagues in South Africa and Brazil. 7) The Center will be a forum for HIV research and policy and will foster strategies for effective bidirectional exchange with various communities. 8) The Center will use a variety of mechanisms that support an train young scientists in multidisciplinary research skills, in sensitivity to culturally diverse norms, and in strategies to respond to the special needs of underserved populations and their communities.